Influence of Cross-Sectional Geometry on Crush Characteristics of Multi-Cell Prismatic Columns

Abstract

Analytical techniques founded on mechanics of progressive collapse of thin-walled structures and nonlinear transient dynamic finite element (FE) simulations are used to study the influence of cross-sectional geometry on the crush characteristics of multi-cell prismatic columns made of ductile materials. An analytical formula for the prediction of mean crush force is derived based on the super folding element model and the associated kinematically consistent representation of plastic collapse in the corner regions. In this model, the isotropic material is treated as rigid-perfectly plastic and the total internal energy is calculated by considering both bending and membrane deformation during the folding process. FE simulations are used to evaluate the force-displacement response, specific energy absorption, crush pattern, and crush distance for different multi-cell, multi-corner models. The geometric features of interest include the arrangement of the interior walls and their connectivity with the outer tube walls that result in acute or obtuse angles. The analytical predictions for the mean crush force are found to be in good agreement with the FE solutions. Results also show a strong correlation between the cross-sectional geometry and the crash behavior with the method of connecting the inner to the outer walls having large influence on the energy absorption.